Field of the Invention
The present invention relates to a method of manufacturing a high-pressure discharge lamp and a sealed part structure for a high-pressure discharge lamp, whereby pressure proof performance in the internal space of the high-pressure discharge lamp can be enhanced.
Background Art
A high-pressure discharge lamp has been widely used for a projector and so forth, and is characterized in that quite a large amount of light is obtainable from a single high-pressure discharge lamp. The high-pressure discharge lamp is generally composed of a sealed container made of silica glass and a pair of mounts. Each mount is composed of an electrode, a metallic foil and an external lead rod. Each mount is formed by welding the electrode to one end of the metallic foil and by welding the external lead rod to the other end of the metallic foil.
The pair of mounts is inserted into the sealed container such that the electrodes thereof are opposed to each other. Then, the mounts are air-tightly sealed by the both end parts of the sealed container. Thus, the both end parts of the sealed container are formed as a pair of sealed parts, while a luminous tube part is formed between the pair of sealed parts. The luminous tube part herein has an internal space in which the paired electrodes are disposed in opposition to each other.
Mercury is encapsulated in the internal space. When high voltage is applied to the pair of mounts, an arc discharge is generated. Accordingly, evaporated mercury is excited and emits light.
The high-pressure discharge lamp is enhanced in luminous efficiency (a luminous amount per electric power to be supplied to the high-pressure discharge lamp) by increasing the pressure of the internal space in lighting. Therefore, it is an important challenge to enhance the pressure proof performance of the sealed parts of the sealed container in the high-pressure discharge lamp. Technologies have been conventionally developed for enhancing the pressure proof performance of the sealed parts (e.g., see Japan Laid-open Patent Application Publication No. JP-A-2001-23570).
In the technology disclosed in the Publication No. JP-A-2001-23570, the pair of mounts, in each of which the metallic foil has been preliminarily covered with a glass tube, is used for enhancing the pressure proof performance of the sealed parts. With use of the mounts as described above, sealing of each mount by the sealed container is conducted between glass members, i.e., the glass tube and the end part of the sealed container. Thus, highly airtight fusion can be achieved in comparison with sealing between different types of materials, i.e., glass and metal. Consequently, the pressure proof performance of the sealed parts can be enhanced.